In the transfer of articles from place to place it is common to use roller conveyors. Some conveyors include rollers which are not powered, whereas other conveyors use rollers which are powered. In either case it is desirable that the upper surfaces of adjacent rollers be coplanar so that each roller may support an equal share of a load and so that passage of an article along the conveyor does not tend to jar the article or shift a roller due to its being at a level higher than the adjacent rollers. It also is desirable that the rollers be capable of yielding when subjected to sudden shock, such as by the dropping of a heavy object onto the conveyor, thereby preventing premature failure of the rollers' bearings.
In those instances in which some or all of the rollers of a conveyor are powered it often is advantageous to include as part of the drive mechanism a clutch which normally transmits rotation from the driver to the roller, but which under certain circumstances permits relative rotation between the driver and the roller. Such an arrangement enables a conveyor to be used as an asynchronous conveyor.
Typical of known conveyors possessing some of the above characteristics are those disclosed in U.S. Pat. Nos. 2,396,079; 2,712,377; and 2,769,515.
One of the disadvantages of known roller conveyor constructions is that they conventionally are manufactured in special lengths and widths for the conveying of specific objects. As a consequence, it is rarely feasible to produce and stockpile component parts of a conveyor and from which different size conveyors can be fabricated. In addition, the shortening or lengthening of conventional conveyors, after initial installation, poses many problems which may be eliminated or minimized by the present construction.